Filter device for antenna systems



June-17, 1947, E; v. AMY ETAL FILTER DEVICE FOR ANTENNA SYSTEMS 2 Sheets-Sheet l Tg5. 5&6

Filed April 4, 1942 ATTORNEY June 17, 1947.

E. V. AMY Erm.

FILTER DEVICE FOR ANTENNA SYSTEMS Filed April 4, 1942 2 Sheets-Sheet 2 INV NTORS E'rzefs MAW y J Las Aceves ATTORNEY Patented June 17, 1947 FILTER DEVICE FOR ANTENNA SYSTEMS Ernest V. Amy and Julius G. Aceves, New York, N. Y., assignors to Amy, Aceves & King, Inc., New York, N. Y., a corporation of New York Application April 4, 1942, Serial No. 437,712

(Cl. Z50-33) 9 Claims.

Our invention relates to antenna systems for use with radio receivers, and more particularly to devices for use in such systems whereby optimum antenna conditions are automatically ob'- tained for different selected frequency bands. The invention is especially useful in receiving radio signals in the different bands greater than 1500 kilocycles.

This application is a continuation in part of our copending application Serial No. 152,864, filed July 10, 1937, now Patent No. 2,282,292, issued May 5, 1942.

According to the aforesaid application, a single antenna, desirably of the dipole type or functi`oning as such, is caused to automatically pron vide maximum signal pick-up for different frequencies or narrow bands of frequencies inter mediate that for which the entire antenna provides maximum response. That is to say, a single dipole may be of a proper overall length to provide maximum voltage for twenty-five meter signals; and by the insertion of dividers, or length limiting devices, in the arms of the dipole, portions of the same antenna will provide maximum or optimum conditions for the reception of signals in the ten and the five meter bands respectively. Such dividers may be anti-resonant, resonant, or comprise inductively coupled elements. The present application pertains to the physical forms of such length limiting devices.

Among the objects of our invention are to provide a simple, compact, easily manufactured and assembled structure which can be readily installed by the general public without danger of improper connections or disturbing the functioning of the device.

Another object of our invention is to provide devices of the above character capable of func tioning properly under all conditions of weather, climate, etc.

In certain of its forms, it is another object of our invention to provide such length limiting devices which are also capable of withstanding the strains and stresses of being an integral part of the aerial suspension system.

In certain other of its forms, it is a further object of our invention to provide for a ready adjustment of the electrical values of the device when it is connected in circuit, so as to compensate for minor corrections, and so that one device may be used in several different locations in an antenna.

Otherl features and advantages of our invention will be apparent from this specication taken inv 2 conjunction with the accompanying drawings, wherein- Figure 1 is a vertical section through one of the devices embodying this invention, certain parts being shown in full lines to facilitate illustration.

Fig. 2 is a plan view of the device of Fig. 1, mounted in operative positionl Fig. 3 is a vertical section through a modified form of device, certain parts being shown in full lines to facilitate illustration.

Fig. 4 is an elevational view of another modified form of a device suitable for the purposes of some applications of the aforesaid antenna system.

Fig. 5 is a sectional view of still another modied form of device in which the electrical characteristics thereof are readily adjustable.

Figs. 6 and '7 are vertical sections through still other modied forms of device according to this invention, certain parts being shown in full lines to facilitate the illustration.

In most cases, the device is illustrated in the accompanying drawings on an enlarged scale so that the showing may be clearer.

Referring to Figs. 1 and 2 of the drawings, the cup-shaped casing II has an internal rib I2 extending around the side walls of the cup and spaced from the closed end thereof. The side walls are provided with a pair of holes I3 located opposite each other and adjacent the open end of the cup I I. A core I4 (preferably composed of powdered iron suitably compacted with an insulating and binding material to form what appears to be a solid bar) has a few turns of wire, forming a coil I5, wound thereon and near one of its ends. The core is centrally mounted in a disc I8, of paper or suitable insulation, which rests on top of rib I2 and divides the cup into a closed chamber and an open chamber.

A condenser I6 has a connecting and mounting lead wire I'I extending from each side thereof and bent upwardly, the ends passing through suitable apertures in the disc I8, so that the condenser and coil are mounted in the closed chamber in the casing Il. The ends of the coil I5 are soldered to the respective lead wires I'I so that, in this example, the coil and condenser are connected in shunt relation to each other in the circuit, these connections also being located within the closed chamber in the casing.

Lead wires I9 and 20 pass through the openings I3 in the cup II and respectively have one end connected to one of the wires II, these connections being located on the opposite side of the disc I8, or in the open chamber of the casing.

To complete the device, the open chamber in the cup I is lled with wax or other suitable sealing compound which is weather resistant and which will protect the elements and the connections from the effects of moisture, ice and snow, that otherwise would affect its electrical values.

The device, construction as just described, may be mounted in place as shown in Fig. 2. A doublet antenna is diagrammatically illustrated in this iigure, the down lead conductors 25 extending from the gap 26 thereof to a radio receiver (not shown) and the device of this invention is shown applied to only one arm of this doublet whereas, as will be understood from the aforesaid application, either or both arms may be provided with the dividers described in this application, or similar devices.

One arm of the doublet is divided in two branches 21 and 21A, the division occurring at a distance from the gap 26 corresponding to one quarter of the wave length of the mid-frequency of the narrow band of intermediate frequencies which it is desired to receive. An insulator 28 has the adjacent ends of the branches 21 and 21A connected thereto, the insulator being of one of the usual types used for mounting aerial wires, and designed to withstand the strain and stresses incident to supporting the Weight of the antenna. The device of Fig. 1 is mounted alongside the insulator 28 and has its lead wires I9 and 2U connected respectively to the branches 21 and 21A of this arm of the dipole.

In this manner the branch 21 of the dipole, usually plus a corresponding portion of the other arm of the dipole, provides maximum signal pick-up for one frequency or narrow band of frequencies, while the branches 21 and 21A, usually together with another arm of the dipole of corresponding length, gives maximum signal voltage for another frequency or narrow band of frequencies; and the selection of the proper portions of the antenna to provide such results is entirely automatic.

One example of the device of Fig. 1 comprises a coil of ten turns of No. 35 D. S. C. wire wound on a inch iron core, and a 25 micro microfarad condenser.

Referring to Fig. 3, the casing comprises a tube 3| of insulation material. A coil form 32, of wood o-r other material, and provided with a coil 33 midway its length, is mounted in a pair of discs 34 that are located on opposite sides of the coil 33. The discs are of a size to iit the interior of the tube 3| leaving a closed central chamber 35 on the interior of the tube between the discs, and open chambers at either end of the tube. A condenser 3B is mounted in the chamber 35 with its lead wires 31 connected across the ends of the coil 33, the condenser capacity being of suitable value corresponding to the value of inductance of the Coil 33 for the particular application to be made. The wires 3'! are suiiciently stiff to constitute the mounting for the condenser 3E.

Lead wires 38 and 39 extend respectively from opposite ends of the coil 33, passing through suitable apertures in the discs 34 and outwardly beyond the ends of the tube 3|.

An eye bolt 4| is screwed into each end of the coil form 32, the eyes thereof being located beyond the ends of the tube 3| and being adapted to receive respectively an end of the branches 42 and 42a of one arm of an antenna. The lead wires 38 and 39 are connected respectively to the branches 42 and 42a. Here, no separate insulator, such as 28 in Fig. 2 need be used, the construction being constructed to be sufficiently strong to take up the stresses and strains of supporting its proportionate share of the weight of the branches 42 and 42a.

To protect the apparatus from the elements, moisture, etc., the open ends 43 of the tube 3| are filled with paraflin, wax, or other suitable sealing material.

The circuit connections of the device of Fig. 3 itself and in the antenna system are the same as described in connection with Fig. 2.

eferring to Fig. 4, there is shown an insulator having apertures 41 near each end thereof. This may or may not be a suspension type of insulator, as desired. Wire is wrapped around the insulator to form a coil 48 of suitable proportions for the particular application, the turns of the coil touching each other. rIhe ends of the coil, or a suitable lead wire, extend outwardly through the apertures 41 for connection to the branches of an arm of a dipole type antenna. One such construction, suitable for use in the systems of the aforesaid application, consists of sixteen turns of No. 18 black enamelled, copper wire wound on a porcelain rod one-half inch in diameter. The distributed capacity of this coil is sufficient for the purposes of the circuit and appears vin the circuit in shunt to the coil.

Referring now to Fig. 5, a metal tube 5| is closed at each end by a disc 52 of insulation material. A pair of eye-bolts 53 for receiving the ends of branches of an arm of a dipole in the i ianner indicated above have their shafts 54 eX- tending centrally through the tube, the same being mounted in each of the end discs 52. Mounted between the discs 52 is a tubular coil form 55 of insulation material, upon which is wound a coil 56 of suitable value, the coils of the wire being arranged to have a distributed capacity sufficient for the purposes of the particular circuit connection. In order to vary the Yimpedance value of the coil with its distributed capacity, an iron core 51, similar to core I4 of Y Fig. l, is mounted inside the coil form 55 and arranged to slide upon the shaft 54. The end of the core 51 is received in a clamp 58 that is carried by an L-shaped arm 59 extending through a slot 6! in the coil form 55 and having its free end arranged to be guided on the interior of the tube 5|. An adjusting screw 6| has one end thereof attached to the arm 59 and a knob 62 at its outer end. The screw 6| is adjustable in a suitable opening in one of the end discs 52. By turning the knob 62 the core 51 slides in and out of the coil 55 to vary its inductance and its distributed capacity.

Fig. 6 shows a construction of a divider wherein the condenser also serves as a housing for the divider. The housing `comprises a pair of metallic, telescoping, closed end cylinders 1| and 12 separated by a collar 13 of suitable insulating material. The closed ends of the cylinders are provided with suitable connecting members 14 and i5 respectively to each of which may be connected the antenna wire 16. An insulator bar 18 iC mounted within the housing, on which is wound the coil 11, the ends of which have pigtail connections to the cylinders 1| and 12 respectively. The housing forms the condenser, the capacity of which may be adjusted by sliding the two cylinders relatively to each other. When the desired value of capacity is obtained for the particular value of inductance, the two cylinders may be secured together in the adjusted position by any suitable means, and an insulating and weather-proofing compound may be poured over the joint to seal the housing and to X the adjustment of the capacity of the condenser.

Fig. 7 shows another construction of divider having an adjustable condenser. In this form a metallic closed end cylinder 8| is closed at its opposite end by a disc 82 of insulating material. Within the cylinder 8| isa post 81 of insulating material, the post being screw threaded at one end and being adjustable in the metallic end of the cylinder 8l. At its outer end the post carries a mounting eyelet 83. At its opposite end the post is internally screw threaded to receive the shank of a mounting eye-bolt S4. The disc 86 is mounted upon the post 8l which disc extends parallel to the end of the metal housing 8l and to .constitute therewith the opposite plates of a condenser. A coil 88 is diagrammatically illustrated as wound upon the core 81 and has one end connected to the metal disc 86 of the condenser. The opposite end of the coil passes through an aperture in the end disc 82 and is connected to a clip engaged by the eye-bolt 84.

The divider is mounted between the branches of the arm 85 of the antenna, and as will be apparent, the coil and condenser are in series circuit relation therewith. I'o adjust the value of the capacity the nut 89 is loosened which permits the disc or plate 85 of the condenser to be adjusted toward or away from the metal end disc of the housing 8l to thereby vary the capacity Value thereof. Thereafter the lock nut 89 is tightened in place to hold the adjustment.

If desired the inductance and condenser may be mounted in separate cases which may be either metal or of dielectric material having low loss characteristics at the frequencies mentioned herein.

Modifi-cations may be made in the arrangement and location of parts within the spirit and scope of my invention, and such modifications are intended to be covered by the appended claims.

I claim:

l.. The combination with an antenna system of the dipole type having at least one arm divided into two branches, an insulator to which the two branches are connected to physically separate the same, of a filter comprising a housing, a magnetic core mounted therein, a coil wound about said core, a condenser in circuit with said coil, lead wires extending from said coil externally of said housing for connection respectively to the branches of said antenna arm, and means for closing said housing.

2. In an antenna system, the combination of an antenna of the dipole type, and a filter in an arm of the antenna located intermediate its ends, said filter comprising a housing, a core mounted therein, a coil wound about said core and having a selected inductance value according to thefreqnency of the signal to be received by one portion of said antenna, a condenser having a similar selected value, circuit connections between the condenser and coil, lead wires from said connections extending outwardly beyond the ends of said housing for connection into the arm of the antenna intermediate its ends to separate the same into branches to provide maximum signal reception for signals of certain frequencies in a portion of said antenna and to automatically permit the entire antenna to function for the reception of other signals at separated frequencies.

3. In an antenna system, the combination of an antenna' of the dipole type, and a filter in an arm of the antenna located intermediate its ends, said filter comprising a housing, a core mounted therein, a coil wound about said core, a condenser, circuit connections between the condenser and coil, lead wires from said connections extending outwardly beyond the ends of said housing for connection into the arm of the antenna intermediate its ends to electrically divide the same into separate branches, the coil having a selected inductance value according to the frequency of the signal to be received by a portion only of said antenna and the condenser having a similar selected value, to provide maximum signal reception for signals of certain frequencies in a portion of said antenna and to automatically permit the entire antenna to function for the reception of signals of other frequencies, and means for suspending the filter between the branches of the arm of the antenna being divided thereby.

4. In an antenna system, the combination of an antenna of the dipole type, and a filter in an arm of the antenna, said filter comprising a housing, a core of insulation material mounted therein, a coil wound about the core, a condenser mounted in the housing and connected in circuit with said coil, means forming a closed chamber about said condenser and coil, lead wires connected to said coil and extending outwardly from the ends of said housing for connection into the arm of said antenna intermediate its ends, and means for sealing said housing against the entrance of moisture, dirt, and the like, into said chamber.

5. In an antenna system, the combination of an antenna of the dipole type, and a filter in an arm of the antenna, said filter comprising a housing, a pair of discs closing the housing at either end, a tubular coil form mounted between the discs, a coil wound about said form, a slot in the form, a magnetic core mounted inside the form, means for movably supporting said core, means adjustable from outside said housing for moving the core relatively to the coil, and lead wires eX- tending from said coil externally of the housing for connection into the arm of said antenna.

6. In an antenna system, the combination of an antenna of the dipole type, and a filter in an arm of the antenna, said filter comprising a housing, a core mounted therein, a coil wound about said core and having a selected inductance value according to the frequency of the signal to be received by one portion of said antenna, a capacity in circuit with said coil having a similarly selected value, lead wires from said coil and eX- tending outwardly beyond the ends of said housing for connection into the arm of said antenna intermediate its ends to separate the same into branches for the reception of certain signals and to automatically permit the entire antenna to function for the reception of other signals, and means whereby the value of the capacity in said circuit may be adjusted readily when the device is being installed.

7. In an antenna system, the combination of an antenna of the dipole type, and a iilter in an arm of the antenna, said filter comprising an insulating enclosure, a core, a coil wound about said core, the coil having a selected inductance value, a capacity in circuit with said coil also having a selected value, and means for suspending said filter from and connecting the same intermediate the ends of said antenna arm, the values of said inductance and capacity and the location of the filter being chosen so that the antenna is electrically severed into separate branches to provide maximum signal pick-up for signals of certain selected frequencies by one portion of the antenna and automatically permit the entire antenna system to function for the elective reception of signals of other and separated frequencies.

8. In an entenna system, the combination of an antenna of the dipole type, and a lter in an arm of the antenna, said lter comprising an insulating enclosure, a core, a coil wound about said core, the coil having a selected inductance Value, a capacity in circuit with said coil also having a selected value, and lead wires from said coil circuit and extending outwardly from said filter, the lead wires being connected into the arm of said antenna so as to electrically divide the same into separate bran-ches, the Values of said inductance and capacity and the location of the lter being chosen so that one branch of the system provides maximum signal pick-up for signals of certain selected frequencies, and automatically the entire system will function for the reception of signais of other and separated frequencies.

9 In an antenna system, the combination of an antenna of the dipole type, and a lter in an arm of the antenna, said lter comprising a housing, a core therein, a coil Wound about said core, the coil having a selected inductance value, a capacity in circuit with said coil also having a selected value, and lead wires from said coil circuit and extending outwardly beyond said housing, the lead wires also being connected into the arm of said antenna so as to electrically divide the same into separate branches, the values of said inductance and capacity and the location of the filter being chosen so that one branch of the system provides maximum signal pick-up for signals of certain selected frequencies, and automatically the entire system will function for the reception of signals of other and separated frequencies.

ERNEST V. AMY.

JULIUS G. ACEVES.

REFERENCES CITED VThe following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,028,596 Franklin et al Jan. 2l, 1936 2,227,846 1Rust Jan. 7,1941 2,132,044 Overacker Oct. 4,1938 2,096,782 Brown Oct. 26, 1937 2,243,182 Amy et al May 27, 1941 1,783,025 Meissner Nov. 25, 1930 1,945,735 Davis Feb. 6, 1934 2,222,406 Crosley Nov. 19, 1940 2,090,026 Bridges Aug. 17, 1937 2,282,292 Amy et al May 5,1942 1,965,539 Amy et al. July 3, 1934 2,176,064 Cole et a1 Oct. 17, 1939 2,130,815 Riepka Sept. 20, 1938 1,957,986 Smith May 8,1934

FOREIGN PATENTS Number Country Date 367,414 Italy 1939 

